In a four-page written confession to police hours after his arrest, Evans said he had watched the remake of "Halloween" three times earlier that week.

The 2007 Rob Zombie film is about a 10-year-old boy who murders several people and kills a number of others 15 years later.

While watching it, I was amazed at how at ease the boy was during the murders and how little remorse he had," Evans wrote. "Afterward, I was thinking to myself it would be the same for me when I kill someone."

Later, as his mother and sister watched the presidential debate that night, he said he "just sat in the living room thinking about how I was going to kill my family."

He wrote that he got a knife.

"I went back upstairs and kept pacing back and forth imagining killing Mallory," he said. "Thoughts of causing her pain kept entering my mind and were really bothering me. But then I'd think about the times she hurt my feelings."

He later knocked on her bedroom door and asked her to watch the comedy movie "Water Boy."

Then he changed his plans.

"After a while, I thought to myself that if I were to kill my mom and Mallory, I wouldn't want them to feel anything, so I decided to kill them both with the .22 revolver I stole from my Grandpa," he wrote.

He said he thought about it some more.

"I then spent probably over an hour walking nervously around the house thinking how life will never be the same and how I would never see them again," he wrote.

He said he knocked on sister's door again and told her their mother needed her.

"She came out and out of the corner of her eye she saw me pointing the gun at her," he said. "She thought I was joking and told me that I was freaking her out. I shot her in the back and then the head."

'Dreadful and terrifying'He then went to the study and shot his mother three times.

"In shock, I ran to my room and was screaming at the top of my lungs that I am really messed up and that I killed my mom and sister," he wrote.

"As I emptied the shells on my bed, I heard noizes (sic) and realized that Mallory was still alive," he said. "While I loaded the gun back up, I was shouting that I was sorry and then ran as fast as I could to kill her. I made sure my mom was dead and shot her again in the head."

He said he placed the gun on the counter and called 911.

Sheriff's deputies found the bodies of his mother and sister and arrested him.

In the last lines of his confession, he wrote: "I know now though that I'm done with killing. It's the most dreadful and terrifying thing I will ever experience. And what happened last night will haunt me forever."